10.1002/anie.201707716
Angewandte Chemie International Edition
COMMUNICATION
Conflict of interest
Table 3. Selected calculated energies for the different possible conformers of compound 8 (D3 = D3BJ(abc), all
methods except PBEh-3c: def2-TZVP basis set).
The authors declare no conflict
of interest.
HF
PBEh
-3c
B3LYP
B3LYP
-D3
PBE0
PBE0
-D3
TPSS
TPSS
-D3
B2PLYP-D3
//TPSS-D3
MP2
anti-anti
0.0
4.3
3.4
9.8
15.0
8.3
7.5
6.5
8.3
0.0
0.0
3.4
2.6
7.6
12.0
10.6
10.1
9.2
0.0
2.3
1.5
5.4
8.7
7.5
7.1
6.1
7.9
0.0
0.0
3.0
2.1
7.0
10.8
8.1
7.7
6.6
8.3
0.0
10.7
10.1
9.4
23.7
21.2
20.3
14.3
0.0
anti-gauche
gauche-anti
gauche-gauche
π-π
Keywords: dispersion interac-
tions • intermolecular π-stack-
ing • bridged arenes • gas elec-
tron diffraction • intramolecular
π-stacking
9.9
10.1
0.0
0.0
Comparison of the experimental molecular structures with quan-
tum-chemically calculated ones (Table 2) shows a significantly
better description by dispersion-corrected methods in case of
the centroid-centroid distances. The calculations that do not
correct for dispersion forces yield a better agreement for the shift
and angle between the phenyl groups. The latter might be
explained by the strong influence of (anharmonic) thermal
motion on these parameters resulting in a discrepancy between
rh1 values determined by GED and calculated ones (re). In
particular, the last system, 8, turns out to be a suitable bench-
mark system for investigation of the influences of intramolecular
π-stacking interactions on the structures of small organic
molecules.
Table 3 lists a selection of calculated conformer energies for
compound 8. The GED experiment for 8 is the most unequivocal
concerning the absence of other conformers. The fact that other
conformers would require energies as close as 10 kJ mol–1 to
the global minimum at the temperature of the experiment
(383 K) to make a contribution of 4% which is about what is de-
tectable by GED shows that energies very significantly below 10
kJ mol–1 are unrealistic. In this respect the methods B3LYP-D3
and B2PLYP-D3//TPSS-D3 seem to do the best job, given that
we expect MP2 to grossly overestimate the role of dispersion.
Our work demonstrates that π-stacking interactions dominate
the solid-state structures of flexibly linked bis(arenes) in a way,
that π-bound intermolecular aggregates are formed. Thus, they
can adopt the conformations, which would be realized for free
molecules in the absence of additional stabilization by dispersion.
By contrast, and similar to the folding of n-alkanes,[21] the free
molecules in the gaseous state seek for stabilization by dispersi-
on through folding and find the optimum in the π-π conformers.
This is then the only conformer that is reliably detectable in gas
electron diffraction experiments. Future work on molecules bea-
ring identical aryl substituents will shed additional light on the
importance of electrostatic compared to dispersion interactions.
___________________________________________________
[1]
[2]
J. P. Wagner, P. R. Schreiner, Angew. Chem. Int. Ed. 2015, 54, 12274.
a) A. Karton, P. R. Schreiner, J. M. L. Martin, J. Comput. Chem. 2016,
37, 49; b) S. Shaik, H. S. Rzepa, R. Hoffmann, Angew. Chem. Int. Ed.
2013, 52, 3020; c) C. E. Check, T. M. Gilbert, J. Org. Chem. 2005, 70,
9828; d) T. Schwabe, S. Grimme, Acc. Chem. Res. 2008, 41, 569; e) M.
D. Wodrich, C. Corminboeuf, P. R. Schreiner, A. A. Fokin, P. v. R.
Schleyer, Org. Lett. 2007, 9, 1851.
[3]
[4]
a) S. Grimme, WIREs Comput. Mol. Sci. 2011, 1, 211; b) N. A. Seifert,
A. L. Steber, J. L. Neill, C. Perez, D. P. Zaleski, B. H. Pate, A. Lesarri,
Phys. Chem. Chem. Phys. 2013, 15, 11468.
a) S. Grimme, J. Comput. Chem. 2006, 27, 1787; b) S. Grimme, J.
Antony, S. Ehrlich, H. Krieg, J. Chem. Phys. 2010, 132, 154104; c) S.
Grimme, S. Ehrlich, L. Goerigk, J. Comput. Chem. 2011, 32, 1456; d) J.
Řezáč, P. Hobza, J. Chem. Theory Comput. 2012, 8, 141.
[5]
[6]
C. R. Patrick, G. S. Prosser, Nature 1960, 187, 1021.
a) E. G. Cox, D. W. J. Cruickshand, J. A. S. Smith, Proc. R. Soc. A
1958, 247, 1; b) N. Boden, P. P. Davis, C. H. Stam, G. A. Wesselink,
Mol. Phys. 1973, 25, 81.
[7]
[8]
a) J. S. W. Overell, G. S. Pawley, Acta Crystallogr. B 1982, 38, 1966; b)
J. H. Williams, J. K. Cockcroft, A. N. Fitch, Angew. Chem. Int. Ed. Engl.
1992, 31, 1655.
a) J. H. Williams, Acc. Chem. Res. 1993, 26, 593; b) T. Dahl, D. Kozma,
M. Ács, J. Weidlein, H. Schnöckel, G. B. Paulsen, R. I. Nielsen, C. E.
Olsen, C. Pedersen, C. E. Stidsen, Acta Chem. Scand. 1994, 48, 95; c)
M. I. Cabaco, Y. Danten, M. Besnard, Y. Guissani, B. Guillot, Chem.
Phys. Lett. 1996, 262, 120; d) J. C. Collings, K. P. Roscoe, R. L.
Thomas, A. S. Batsanov, L. M. Stimson, J. A. K. Howard, T. B. Marder,
New J. Chem. 2001, 25, 1410.
[9]
a) M. O. Sinnokrot, C. D. Sherrill, J. Am. Chem. Soc. 2004, 126, 7690;
b) B. W. Gung, J. C. Amicangelo, J. Org. Chem. 2006, 71, 9261; c) S.
Tsuzuki, T. Uchimaru, M. Mikami, J. Phys. Chem. A 2006, 110, 2027;
d) R. G. Huber, M. A. Margreiter, J. E. Fuchs, S. v. Grafenstein, C. S.
Tautermann, K. R. Liedl, T. Fox, J. Chem. Inf. Model. 2014, 54, 1371.
[10] a) J. Hernández-Trujillo, F. Colmenares, G. Cuevas, M. Costas, Chem.
Phys. Lett. 1997, 265, 503; b) A. P. West, S. Mecozzi, D. A. Dougherty,
J. Phys. Org. Chem. 1997, 10, 347; c) S. Lorenzo, G. R. Lewis, I.
Dance, New J. Chem. 2000, 24, 295; d) O. R. Lozman, R. J. Bushby, J.
G. Vinter, J. Chem. Soc., Perkin Trans. 2 2001, 1446.
[11] F. Cozzi, J. S. Siegel, Pure Appl. Chem. 1995, 67, 683.
[12] F. Cozzi, R. Annunziata, M. Benaglia, K. K. Baldridge, G. Aguirre, J.
Estrada, Y. Sritana-Anant, J. S. Siegel, Phys. Chem. Chem. Phys. 2008,
10, 2686.
Acknowledgements
The authors thank Dr. Christian G. Reuter for maintenance of
the gas electron diffractometer at Bielefeld University, Dipl.-Ing.
Klaus-Peter Mester and Gerd Lipinski for recording NMR spectra
Heinz-Werner Patruck for measuring mass spectra, Brigitte
Michel for CHN analyses. We gratefully acknowledge financial
support from the Deutsche Forschungsgemeinschaft through the
SPP1807 (Mi477/28-1) and core facility GED@Bi (Mi477/35-1).
[13] a) J.-H. Lamm, J. Horstmann, H.-G. Stammler, N. W. Mitzel, Yu. A.
Zhabanov, N. V. Tverdova, A. A. Otlyotov, N. I. Giricheva, G. V.
Girichev, Org. Biomol. Chem. 2015, 13, 8893; b) a related system with
interacting Me3Si groups: N. W. Mitzel, V. V. Rybkin, Yu. A. Zhabanov,
N. V. Tverdova, N. I. Giricheva, G. V. Girichev, Phys. Chem. Chem.
Phys. 2017, 19, 13093.
[14] I. Ojima, T. Fuchikami, M. Yatabe, J. Organomet. Chem. 1984, 260,
335.
This article is protected by copyright. All rights reserved.